The present invention relates generally to the field of underground boring and, more particularly, to a system and method of altering operation of an underground boring system, including disabling drill string movement and fluid flow through the drill string, from a location remote from the boring system.
Utility lines for water, electricity, gas, telephone, and cable television are often run underground for reasons of safety and aesthetics. In many situations, the underground utilities can be buried in a trench which is then back-filled. Although useful in areas of new construction, the burial of utilities in a trench has certain disadvantages. In areas supporting existing construction, a trench can cause serious disturbance to structures or roadways. Further, there is a high probability that digging a trench may damage previously buried utilities, and that structures or roadways disturbed by digging the trench are rarely restored to their original condition. Also, an open trench may pose a danger of injury to workers and passersby.
The general technique of boring a horizontal underground hole has recently been developed in order to overcome the disadvantages described above, as well as others unaddressed when employing conventional trenching techniques. In accordance with such a general horizontal boring technique, also known as microtunnelling, horizontal directional drilling (HDD) or trenchless underground boring, a boring system is situated on the ground surface and drills a hole into the ground at an oblique angle with respect to the ground surface. A drilling fluid is typically flowed through the drill string, over the boring tool, and back up the borehole in order to remove cuttings and dirt. After the boring tool reaches a desired depth, the tool is then directed along a substantially horizontal path to create a horizontal borehole. After the desired length of borehole has been obtained, the tool is then directed upwards to break through to the earth""s surface. A reamer is then attached to the drill string which is pulled back through the borehole, thus reaming out the borehole to a larger diameter. It is common to attach a utility line or other conduit to the reaming tool so that it is dragged through the borehole along with the reamer.
Another technique associated with horizontal directional drilling, often referred to as push reaming, involves attaching a reamer to the drill string at the entry side of a borehole after the boring tool has exited at the exit side of the borehole. The reamer is then pushed through the borehole while the drill rods being advanced out of the exit side of the borehole are individually disconnected at the exit location of the borehole. A push reaming technique is sometimes used because it advantageously provides for the recycling of the drilling fluid. The level of direct operator interaction with the drill string, such as is required to disconnect drill rods at the exit location of the borehole, is much greater than that associated with traditional horizontal directional drilling techniques.
It can be appreciated that unintended movement of the drill string and/or cutting head at the exit location of the bore may represent a significant hazard to workers at the exit location. A suggested approach to addressing the potential hazards facing workers at the exit location of a bore involves the use of a device that permits a worker at the exit location to terminate advancement or rotation of the drill string/cutting head. Although such an approach would appear to allow the worker to terminate drill string/cutting head advancement and/or rotation, this and other known approaches to addressing the problem of unintended drill string/cutting head movement at the exit location fail to provide unambiguous assurance to the worker at the exit location that the instruction to terminate drill string/cutting head advancement/rotation has been received by the drilling machine.
Such conventional and suggested approaches also fail to provide unambiguous assurance to the worker at the exit location that the steps required to disable drill string/cutting head advancement/rotation at the drilling machine have been successfully completed. Further, such conventional and suggested approaches fail to provide unambiguous assurance to the worker that all drill string/cutting head advancement/rotation will remain disabled, particularly in circumstances where the drilling machine engine is intentionally or unintentionally shut-off and then turned-on or where communication connectivity between the worker and the drilling machine is suspect or lost. Moreover, the potential hazard of dispensing high-pressure drilling fluid at the exit location remains unaddressed by such conventional and suggested approaches.
There exists a need in the excavation industry for an apparatus and methodology for preventing drill string/cutting head movement and, in addition, disabling cutting fluid flow by a worker situated remotely from the drilling machine. There exists the further need for such an apparatus and methodology that provides unambiguous assurance to the worker that all drill string/cutting head movement and fluid flow will remain disabled until such time as the worker participates with the drilling machine operator to purposefully enable the drilling machine for normal operation. There exists yet an additional need for such an apparatus and methodology that enables the drilling machine operator to perform certain limited drilling machine operations, while ensuring that all drill string/cutting head movement is disabled. The present invention fulfills these and other needs.
The present invention is directed to systems and methods for remotely altering operation of a horizontal directional drilling machine, including remotely preventing and/or limiting movement of a cutting head or reamer and disabling dispensing of fluid, foam and/or air into the borehole. A lockout signal is transmitted from a location remote from the drilling machine, preferably by use of a portable or hand-manipulatable remote unit operated by an operator remotely situated with respect to the drilling machine. The lockout signal transmitted by the remote unit is received at the drilling machine. In response to the received lockout signal, a controller of the drilling machine prevents movement of the drill string, such as by disabling displacement and rotation of the drill string to which the cutting head or reamer is coupled. The controller also disables dispensing of fluid, foam and/or air into the borehole in response to the received lockout signal.
The controller effects transmission of a verification signal from the drilling machine to the remote location. The verification signal indicates successful receipt of the lockout signal by the drilling machine, prevention of all drill string movement, and disablement of fluid, foam and/or air supply into the borehole. The remote unit, in response to the verification signal received from the drilling machine, communicates to a user of the remote unit one or more of a visual, audible, and/or tactile indication that the verification signal has been received. Receipt of the verification signal and communication to the remote user of same provides unambiguous assurance to operators working on or proximate the drill string and, in particular, the cutting head or reamer that all drill string/cutting head/reamer movement and, if applicable, fluid dispensed into the borehole has been successfully disabled.
According to another mode of operation, the controller, in response to a lockout signal, prevents all drill string movement, yet provides for limited drilling machine functionality in connection with drill rod manipulation. A drill rod manipulation mode of operation provides for assured prevention of downhole drill string movement, while providing for limited drilling machine functionality, such as automated or manual loading of a new rod to the drill string or returning a rod to storage and preparing to retrieve the next rod. When operating the drilling machine in a drilling rod manipulation mode, movement of the drill string is prevented by use of a clamping mechanism at the drilling machine. After successful clamping of the drill string is verified, such as by use of a sensor at the clamping mechanism, the driving apparatus of the drilling machine may be operated to perform certain tasks. One such task involves loading a new rod for addition to the drill string and manipulating the newly loaded rod so as to thread the new rod to the drill string. In a preferred embodiment, the driving apparatus is purposefully limited in terms of torque and/or thrust to ensure that the clamping apparatus maintains the drill string in a non-moving state during rod manipulation (e.g., when rods are threaded and/or unthreaded from the drill string).
A system and method according to the present invention may further provide a number of additional features that enhance operational integrity and safety. One or more of a visual, audible and/or tactile warning indication, for example, may be communicated to a user of the remote unit in response to a change of state at the drilling machine that affects movement of the drill string and/or supply of fluid, foam and/or air to the cutting head. One or both of a visual and/or audible indication of receipt of the lockout signal transmitted from the remote unit may be communicated to an operator of the drilling machine.
A timer may be provided in the remote unit which is programmed to have a pre-established timeout period. The timer is activated upon transmission of the lockout signal by the remote unit. One or more of a visual, audible, and/or tactile warning indication is communicated to the remote user in response to the remote unit receiving the verification signal from the drilling machine after expiration of the pre-established timeout period following transmission of the lockout signal.
A loss of communication connectivity between the drilling machine and the remote location is preferably detected by the remote unit. One or more of a visual, audible and/or tactile indication of a loss of communication connectivity between the drilling machine and the remote location is communicated to a user at the remote location. An indication of the relative strength of a signal transmitted from the drilling machine and received at the remote location may also be determined and indicated to the remote user.
The remote unit may further provide a remote operator with the ability to alter operation of the drilling machine in a variety of ways, such as by instructing the drilling machine to operate in one of a number of selectable operating modes. An operating mode signal representative of a user selected operating mode is transmitted by the remote unit and received at the drilling machine. In response to the operating mode signal, the operation of the drilling machine is altered according to the selected operating mode. Altering drilling machine operation may be effected automatically or in response to user control inputs at the drilling machine.
The operating mode signal may, for example, comprise a CREEP mode signal, In response to the CREEP mode signal, the controller of the drilling machine reduces one or both of cutting head or reamer rotation and/or displacement from a nominal level to a pre-established level. The operating mode signal may further comprise one of a PUSH, PULLBACK or ROTATE mode signal. The controller alters a rate and/or force of forward cutting head or reamer displacement in response to the PUSH mode signal, alters a rate and/or force of reverse cutting head or reamer displacement in response to the PULLBACK mode signal or alters a rate of cutting head or reamer rotation in response to the ROTATE mode signal. The operating mode signal may also comprise a STEERING mode signal. The controller of the drilling machine effects boring tool heading changes in response to the STEERING mode signal. A steering control provided on the remote unit may comprise a plurality of switches each representative of a position on a clock face. The STEERING mode signal generated by the steering control is representative of a desired cutting head steering direction corresponding to the position of the actuated switch on the clock face.
The above summary of the present invention is not intended to describe each embodiment or every implementation of the present invention. Advantages and attainments, together with a more complete understanding of the invention, will become apparent and appreciated by referring to the following detailed description and claims taken in conjunction with the accompanying drawings.